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This avoids unexpected failures with no or poor error messages.

Comments may consist of more than one line.  So far, only the first
line was deleted without fixing brackets thus corrupting the file.
From now on, the comments are deleted as a whole.

Additionally, pre match substitutions with simple patterns for speed.

In case the new filename path is relative to the current working
directory, remove the preceding dot and slash before comparison.
Furthermore, bibtex files have a .pdf.bib suffix.

Add both standard and error output to be sure an error
is reported also in case of unexpected error messages.

Slashes must be removed from the non directory part only.

If some file is not ordered, return a failure code.

For now do neither crop ascii nor unicode page ranges.

Correctly print et al. also if fornames are printed first.

The new substituion rule most times strips an arbitrary number
of macros with arbitrary nesting on several lines correctly.